Climate change mitigation is any human action that reduces the sources of or enhances the sinks of greenhouse gases. Several strategies may mitigate the effects of greenhouse-gas emissions on the planet. Emissions can be decreased by lowering energy demands, making existing energy systems more efficient, increasing the contribution of renewable forms of energy production, or all of the above. The greenhouse gas methane can be captured and burned to convert it, in effect, into less-harmful CO2, while CO2 can be captured and stored in underground reservoirs where it cannot affect the atmosphere (i.e., sequestered).
Historical Background and Scientific Foundations
The Kyoto Protocol to the United Nations Framework Convention on Climate Change (UNFCCC) was adopted by most of the world's nations in 1997 in Kyoto, Japan. It is the most prominent, yet controversial, international agreement addressing the issue of global climate change. Countries included in the protocol agreed to reduce their anthropogenic greenhouse-gas emissions (carbon dioxide, methane, nitrous oxide, hydrofluorocarbons, perfluoro-carbons, and sulfur hexafluoride) by at least 5% below 1990 levels in the commitment period of 2008 to 2012.
Supporters believe these restrictions are sufficient at reducing greenhouse-gas emissions, while detractors argue that the restrictions do not do enough to mitigate the problem. In addition, a few countries, such as the United States (one of the top greenhouse gas polluters), have not yet ratified the agreement.
Impacts and Issues
The Intergovernmental Panel on Climate Change (IPCC) released its Fourth Assessment Report in fall 2007, with over 700 pages devoted to strategies for short-term (until the year 2030) and long-term (after 2030) mitigation of climate change. The report discussed key mitigation technologies and practices by sector, which includes energy supply, transport, buildings, industry, agriculture, forestry, and waste.
Mitigation strategies for the energy supply sector, for example, include the improvement of energy supply and distribution efficiency, the switching of fuel supplies from coal to gas, and the development of renewable energy, including heat and power industries such as hydropower, solar, wind, geothermal, nuclear, and bio-fuel energy. Biofuels and nuclear power are controversial because of possible side effects.
Changes in transport include the production of more fuel-efficient vehicles, such as hybrids, shifts in public transportation from individual cars to rail and public transport, increasing incentives and infrastructure for non-motorized transport such as walking and biking, and increasing the efficiency of aircraft. Mitigation strategies in the forestry sector include increasing reforestation, decreasing deforestation, and increasing the use of wood products as biofuels in order to displace some fossil fuel usage. Changes in the waste sector include creating incentives for recycling, organic composting, and decreasing waste in general, as well as developing technologies for landfill methane recovery.
WORDS TO KNOW
ANTHROPOGENIC: Made by people or resulting from human activities. Usually used in the context of emissions that are produced as a result of human activities.
BIOFUEL: A fuel derived directly by human effort from living things, such as plants or bacteria. A biofuel can be burned or oxidized in a fuel cell to release useful energy.
DEFORESTATION: Those practices or processes that result in the change of forested lands to non-forest uses. This is often cited as one of the major causes of the enhanced greenhouse effect for two reasons: 1) the burning or decomposition of the wood releases carbon dioxide; and 2) trees that once removed carbon dioxide from the atmosphere in the process of photosyn-thesis are no longer present and contributing to carbon storage.
INTERGOVERNMENTAL PANEL ON CLIMATE CHANGE (IPCC): Panel of scientists established by the World Meteorological Organization (WMO) and the United Nations Environment Programme (UNEP) in 1988 to assess the science, technology, and socioeconomic information needed to understand the risk of human-induced climate change.
KYOTO PROTOCOL: Extension in 1997 of the 1992 United Nations Framework Convention on Climate Change (UNFCCC), an international treaty signed by almost all countries with the goal of mitigating climate change. The United States, as of early 2008, was the only industrialized country to have not ratified the Kyoto Protocol, which is due to be replaced by an improved and updated agreement starting in 2012.
RENEWABLE ENERGY: Energy obtained from sources that are renewed at once, or fairly rapidly, by natural or managed processes that can be expected to continue indefinitely. Wind, sun, wood, crops, and waves can all be sources of renewable energy.
SINK: The process of providing storage for a substance. For example, plants—through photosynthesis—transform carbon dioxide in the air into organic matter, which either stays in the plants or is stored in the soils. The plants are a sink for carbon dioxide.
IN CONTEXT: INSUFFICIENT MITIGATION
“With current climate change mitigation policies and related sustainable development practices, global GHG [greenhouse gas] emissions will continue to grow over the next few decades (high agreement, much evidence).”
SOURCE: Metz, B., et al, eds. Climate Change 2007: Mitigation of Climate Change. Contribution of Working Group III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change New York: Cambridge University Press. 2007.
The IPCC's 2007 report concluded that stabilization by 2100 of greenhouse-gas concentrations between 445 parts per million (ppm) and 535 ppm with their proposed mitigation strategies would cost no more than 3% of the global gross domestic product.
Metz,B.,et al,eds. Climate Change 2007: Mitigation of Climate Change: Contribution of Working Group III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. New York: Cambridge University Press, 2007.
Brown, Sandra, et al. “Changes in the Use and Management of Forests for Abating Carbon Emissions: Issues and Challenges under the Kyoto Protocol.” Philosophical Transactions of the Royal Society of London 360 (2002): 1593–1605.
Smith, Steven J., et al.“A New Route Toward Limiting Climate Change?” Science 290 (2000): 1109–1110.
Topfer, Klaus. “Whither after the Hague?” Science 291(2001): 2095–2096.
“Contribution of Working Group III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change: Mitigation of Climate Change.” Intergovernmental Panel on Climate Change,2007. <http://www.mnp.nl/ipcc/pages_media/AR4-chapters.html> (accessed November 8, 2007).